[NFC][CODEOWNERS] Update codeowners (#997)

* Assign top level items uncovered by others to myself

In theory this should never happen for this project since we contribute
tests to SYCL dir only which is covered by @llvm-reviewers-runtime

Author: Pavel Chupin

.github/CODEOWNERS

@@ -1,9 +1,8 @@
-* @vladimirlaz @romanovvlad @bader
+* @pvchupin
 
 # Use runtime team as the umbrella for most of the tests
 /SYCL/ @intel/llvm-reviewers-runtime
 
-
 # SYCL sub-directory matchers are grouped by code owner first, followed by
 # alphabetical order within the group. Please, keep this ordering.